小鼠生后不同发育阶段附睾组织中Crb3的表达

应用HE染色法和免疫荧光组织化学技术分别对小鼠生后不同发育阶段附睾组织结构及Crb3在不同发育时期附睾组织中的定位表达进行了研究。结果显示,附睾在4周龄时上皮为2层～3层的假复层纤毛柱状细胞,顶端纤毛细长;6周龄上皮细胞层数减少至1层～2层;8周龄附睾管上皮厚度增至最大,上皮细胞呈单层高柱状;12周龄后附睾管上皮开始变薄,呈单层柱状。免疫荧光染色结果显示,Crb3蛋白主要分布在附睾上皮柱状细胞的胞膜,在精子尾部有微弱的表达,这提示了Crb3不仅与附睾上皮细胞的极性建立和维持有关,而且对精子活力和血-附睾屏障的形成也可能具有潜在的影响。     

Morphologic changes in the bursa of fabricius of chickens after inoculation with infectious bursal disease virus.

Sequential morphologic changes in the bursa of Fabricius were studied after oral inoculation of 1-day-old chicks with infectious bursal disease virus (IBDV). The epithelial surface morphology was studied by scanning electron microscopy, whereas the IBDV replication was sequentially followed by immunofluorescence and transmission electron microscopy. The earliest detectable changes in the bursal epithelium were evident at postinoculation hour (PIH) 48. They were characterized by reduction in numbers and size of microvilli on the epithelial cells accompanied by gradual involution of the button-like bursal follicles. At PIH 96 some specimens showed localized surface erosions due to loss of epithelial cells. As the damage progressed, the infolding of the buttomlike follicles became more pronounced and the surface erosions became more extensive. Loss of surface epithelium exposed the underlying damaged bursal follicles which appeared to be bounded by columnar epithelium. Some follicles had lost almost all the lymphocytes and macrophages and appeared as empty craters. Intrafollicular replication of IBDV was detectable as early as PIH 24 by immunofluorescence technique. Viral replication primarily took place in the lymphoid follicles. Regeneration of the follicles was not seen up to postinoculation day 12, suggesting that the IBDV-induced bursal damage could be permanent.     

Light and electron microscopical observations on the terminal airways and alveoli of the lung of the SA (Cape) fur seal Arctocephalus pusillus

During activities of the Sea Fisheries Research Institute at Kleinzee, lung samples from six South African fur seals were collected. The terminal airways showed pseudostratified ciliated columnar epithelium with numerous goblet cells and occasional brush cells. Smooth muscle, cartilage and submucosal glands were also present. The epithelium changed over a short distance, in the smaller airways, through pseudostratified columnar non-ciliated to simple cuboidal epithelium with no goblet cells. The columnar non-ciliated cells contained secretory granules, which appeared to be serous. No Clara cells were found. Cartilage and muscle were present throughout, up to the origin of the alveolar ducts, but the glands disappeared together with the goblet cells. Alveoli were lined by types one and two alveolar epithelial cells, with subepithelial capillaries. They were divided by an alveolar septum with a well developed alveolar knob. This knob contained elastic fibres and fibroblasts, but not the smooth muscle cells which are present in terrestrial mammals and in Phocidae.     

Histological observations of the reproductive organs of the male dog from birth to sexual maturity.

Development of the testis, epididymis and prostate in 53 male beagles was examined histologically with PAS-hematoxylin stain from birth to sexual maturity. The diameter of the seminiferous tubules of the testes was less than 100 microns until 20 weeks of age, however, it increased markedly between 22 and 28 week of age, reaching 180 +/- 7 (mean +/- SD) microns at 28 weeks of age. Only Sertoli cells and gonocytes (or spermatogonia) were detected in the seminiferous tubules until 16 weeks of age. Spermatocytes and spermatids appeared in the tubules at 20 and 22 weeks of age, respectively. Spermatozoa were first observed in the testes of 2 of the 5 dogs at 26 weeks of age and were found in the testes of all the 3 dogs at 28 weeks of age. The diameter of the ducts in the cauda epididymidis was 146 +/- 4 microns at 20 weeks of age. Thereafter it increased markedly, reaching 341 +/- 14 microns at 28 weeks of age. The height of the epithelium and stereocilia in the ducts of the caput epididymidis increased markedly at about 28 weeks of age. A large number of spermatozoa was seen in the lumens of the ducts of the corpus and cauda epididymidis after 32 weeks of age. The shape of the lumens in the glandular alveoli of the prostate became irregular as a result of projection of the glandular epithelium into the enlarged lumens and the epithelial cells of the alveoli became PAS-positive at 24 weeks of age.(ABSTRACT TRUNCATED AT 250 WORDS)     

内蒙古白绒山羊皮肤毛囊发生发育规律的研究

本文研究了内蒙古白绒山羊从胎儿期到生后期皮肤毛囊的发生发育规律。在胎儿期，从４５日龄开始，每隔１５ｄ，用剖腹产手术的方法取胎儿３～５只，分别在头顶、颈上　甲、背、荐、颈侧、肩、体侧、股和腹等１０个部位采取约１×１ｃｍ的皮肤样本；生后期分初生、１～９个月、１岁、１岁半、２岁和３岁等１４个阶段，每阶段在活羊体侧部采取约１×１ｃｍ的皮肤样本。用石蜡切片法制做皮肤切片。经显微观测，得到如下结果：初级毛囊在胎儿期４５日龄前发生，次级毛囊在７５日龄前发生，皮脂腺和汗腺在７５日龄时出现，竖毛肌在９０日龄出现，粗毛１０５日龄时在全身各部位长出，绒毛在１２０日龄时长出。表皮在６０～７５日龄时形成完整结构，真皮层在７５～９０日龄时分化出乳头层和网状层。初级毛囊的发育在胎儿期１３５日龄时已完成，而次级毛囊发育直至出生后６月龄。毛囊群结构主要为三毛型，少数其它毛型。初次级毛囊比例为１：７～１３。     

Effects of age and of early lighting on ovarian function in breeding turkeys

1. Yellow follicle numbers and production of defective egg shells were greater in the early part of the laying period in conventionally-reared turkeys photostimulated at 24 rather than 30 weeks of age. 2. The number of yellow follicles declined with age and were similar in both groups at 40 weeks of age. 3. At 55 weeks of age more birds photostimulated at 24 weeks were out of lay and birds in lay had fewer yellow follicles and more atresia compared with turkeys photostimulated at 30 weeks of age. 4. The numbers of white follicles in the 1 to less than 2 mm size were similar in the two groups at each age. The proportion of white follicles which were atretic was negatively related to the number of yellow follicles, particularly in follicles 5 to less than 8 mm diameter.     

Histology, immunohistochemistry and ultrastructure of the equine tubal tonsil

The tubal tonsil of the horse surrounds the pharyngeal opening of the eustachian tube and is lined by pseudostratified columnar ciliated epithelium interspersed with areas of follicle-associated epithelium (FAE) heavily infiltrated by lymphocytes but devoid of goblet and ciliated cells. Scanning and transmission electron microscopy revealed microvillous cells and cells with features characteristic of M cells such as reduced microvilli or depressed bare surface, more numerous mitochondria, small vesicles and lysosomes, as well as vimentin filaments and epitopes specific for GS 1-B4 as previously seen in the nasopharyngeal tonsil. M cells were also identified in areas of respiratory epithelium not associated with lymphoid follicles and appeared to be the nasal mucosal counterparts of recently described intestinal villous M cells in the mouse. The underlying lymphoid tissue of the FAE was generally organized as solitary lymphoid follicles without germinal centres in contrast to the diffuse and large amount of organized lymphoid follicles with germinal centres that characterize the nasopharyngeal tonsil. CD8+ T and B-lymphocytes were much fewer than in the nasopharyngeal tonsil. High endothelial venules were mainly oriented towards the parafollicular area and contained much fewer endothelial pores and vesiculo-vacuolar organelles. Finally, scattered small clusters of mucus acini and striated muscles were other features that differentiated the tubal and nasopharyngeal tonsils.     

Changes in ovarian function of female turkeys photostimulated at 18, 24 or 30 weeks of age and fed ad libitum or restricted until point of lay.

1. Females from a medium body weight strain of turkeys were fed ad libitum or restricted to 0.6 of ad libitum-fed body weight at sexual maturity and were photostimulated at 18, 24 or 30 weeks of age. Ovarian follicular structure was assessed in 8 birds from both rearing treatments at photostimulation, after photostimulation for 6 or 12 weeks and at 55 weeks of age. 2. The patterns of small white follicles and of larger yellow follicles were similar in restricted and in ad libitum-fed turkeys for birds in lay at the same age, regardless of the time elapsed since photostimulation. 3. Among birds in lay the number of normal yellow follicles and the proportion of multiple yellow follicles declined with age. A relatively low proportion of restricted birds photostimulated at 18 and 24 weeks were in lay after 12 weeks of photostimulation. 4. For birds in lay the number of white follicles 1.4 to less than 1.8 mm in diameter increased and the number greater than 1.8 mm declined with age. There was a corresponding increase in the rates of atresia in follicles 1.8 to less than 5.0 mm in diameter.     

Histological studies on the regional postnatal differentiation of the epididymis in the ram.

The regional postnatal development of the epididymal duct was studied with histological technique in 22 lambs of the “Swedish Landrace” breed at intervals from 1 week to 18 weeks after birth. At one week, the whole epididymal duct had a simple low columnar epithelium. In the terminal segment the epithelium ecquired a structure similar to that in the adult epididymis at the age of about 6 weeks. Normal spermatozoa were not seen in the cauda epididymidis until the lambs were about 18 weeks old. In the middle segment, distal, intermediate and proximal parts, the epithelium increased gradually in height and reached the adult type at about 12, 15 and 18 weeks, respectively. At about 12 weeks of postnatal life, the epithelium of the initial segment increased rapidly in height, at the same time as a distinct lumen formed in the seminiferous tubules. As far as histological features were concerned, the initial segment showed the adult type when the lambs were about 18 weeks old. The presence of spermatozoa in the cauda epididymidis indicates that the lambs readied sexual maturity at this age. It was concluded that the postnatal differentiation of the ram epididymis starts in the terminal segment and then ascends through the middle and initial segments.     

Histomorphological,ultrastructural and morphometrical age-related changes of fundic region of New Zealand rabbits (Oryctolagus cuniculus)

This study investigated the histomorphological, ultrastructural and morphometrical postnatal developmental changes in the rabbit fundic region, especially during changing of the feeding intake. Seventy-two New Zealand rabbits (V-Line breed) at the ages of 1, 7, 15, 23, 30 and 60 days were obtained for light and electron microscopy and morphometric studies of the fundic region. The newborn rabbit's fundic wall was thin and organized into mucosa, submucosa, musclosa and serosa, with a significant increase in thickness with ageing. The fundic glands were few at the first week of life, then increased in length and diameter compared to the preceding age with prominent zonation at 23 days. The gastric pits appeared wide and deep at the first week of life then became typically narrow and shallow at the third week. The mucous cells were the main cell types lining the fundic glands in the first week of life. These cells showed remoulding with a marked increase in Periodic Acid–Schiff reactivity with age. Parietal cells were differentiated earlier (on the first day of life) than the chief cells and distributed at the neck and basal zones. Chief cells differentiated at 15 days old at the base of the glands, followed by an increase in the number and activity. Few active enteroendocrine cells were first seen at 15 days old and then widely distributed throughout the glands. Conclusion: Pronounced histomorphological changes in the fundic mucosal layer, especially the surface and glandular epithelium, correlate with the postnatal rabbit-feeding intake changes.     

Impaired Development of Somatotropes, Lactotropes and Thyrotropes in Growth-Retarded (grt) Mice

Congenitally primary hypothyroid growth-retarded (grt) mice exhibit a characteristic growth pause followed by delayed onset of pubertal growth. We characterized the developmental pattern of somatotropes, lactotropes and thyrotropes in the anterior pituitary, as well as plasma levels of their secretory hormones, in grt mice. Compared with normal mice, the weight of grt pituitary gland was similar at 8 weeks of age but significantly heavier after 12 weeks of age. Compared with normal mice, there were significantly fewer somatotropes in the grt pituitary until 8 weeks of age, but the number gradually increased up to 48 weeks. The number of lactotropes in grt mice was consistently lower than that in normal mice from 2 through 48 weeks, whereas the number of thyrotropes in the grt pituitary was consistently higher than in the normal pituitary. Thyrotropes in the grt pituitary exhibited hypertrophy and hyperplasia with less intensive thyroid-stimulating hormone (TSH) immunoreactivity than normal thyrotropes. In normal mice, the sum of the relative proportions of these cells plateaued at 8 weeks, where it remained up to 48 weeks of age. In grt mice, these proportions almost reached normal levels at 12 weeks of age but gradually declined after 24 weeks. Plasma growth hormone concentrations did not differ between grt and normal mice until 24 weeks of age. Compared with normal mice, grt mice exhibited significantly lower plasma prolactin and thyroxine levels but higher TSH levels. These findings indicate that development of somatotropes, lactotropes and thyrotropes in grt mice is impaired, being followed by altered hormone secretion.     

Influence of follicular ablation during lactation on postweaning interval to estrus, ovulation rate, and endocrine function in sows

Duroc sows farrowed second litters in March and lactated 35 +/- 2 days. At 36 hr before weaning, electrocautery of follicles greater than or equal to 3 mm in diameter (n = 8) or sham surgery (n = 5) was performed to test the hypothesis that ablation of medium-sized follicles would prolong the duration of postweaning anestrus. Number of follicles and diameters at surgery were: 1.3 +/- .6 (greater than 5 mm diameter), 26 +/- 1 (3 to 5 mm) and greater than 20 (less than 3 mm). Blood samples were collected at 15 min intervals for 3 hr beginning at -12, 0, 12, 60 and 96 hr from weaning. Interval to estrus was 3.4 +/- .2 days in seven of eight cauterized sows and 3.6 +/- .6 days for sham-surgery sows. The remaining cauterized sow was anestrus at slaughter, 40 days after weaning. Number of corpora lutea and pregnancy rate were 15.8 +/- .6 and 92%, respectively, and were similar between sham-surgery and cauterized sows. Concentration of follicle stimulating hormone (FSH) at 12 hr before weaning was greater in sows subjected to electrocautery than for sham-surgery sows, but FSH values were similar at other sampling times. Concentrations of estradiol were similar at all times for both treatment groups. Luteinizing hormone (LH) was higher (P less than .05) at 60 hr in cauterized sows because of the onset of the preovulatory LH surge in one sow. We conclude that destruction of medium-sized ovarian follicles before weaning did not influence postweaning reproductive performance.     

Experimental oral Salmonella dublin infection in calves. A bacteriological and pathological study.

Groups of calves (6-7, 12-14 and 24-28 weeks old) were orally infected with different numbers of the virulent Salmonella dublin strain SVA47. For the 6-7 weeks old calves the LD50-dose was estimated to be 1 x 10(7) bacteria. A dose of 10(9) bacteria was lethal within 24 hrs with the calves dying from septicemia and an acute necrotizing panenteritis. Calves 12-14 weeks old given 2 x 10(10) SVA47 bacteria succumbed to a progressive enteritis within one week. The 24-28 weeks old calves were resistant to an infective dose of 1 x 10(10) SVA47 bacteria. In the 6-7 and 12-14 weeks old calves SVA47 could be recovered from the entire intestinal tract, the liver and the spleen. In the oldest calves S. dublin SVA47 was recovered only from fecal specimens. However, the immunohistopathological examinations, using an S. dublin O-antigen-specific mouse monoclonal antibody and PAP-staining, showed the presence of S. dublin SVA47 in all tissues of the intestinal canal from calves of all ages and with a special affinity for the columnar enterocytes of the terminal jejunum and ileum, the follicle-associated epithelium over the Peyer's patches, and glandular tissues in the duodenum, tonsillar area and the lungs. Surviving calves responded with serum antibody titers against the O-antigenic lipopolysaccharide which appeared in the order IgM followed by IgA, IgG1 and IgG2.     

Plasma prolactin, LH, FSH and estrogen excretion patterns in gilts during sexual development

Plasma prolactin (PRL), luteinizing hormone (LH) and follicle stimulating hormone (FSH) were measured by radioimmunoassay in groups of eight gilts sampled every 20 min for 6 h at about 2-wk intervals between 15 and 192 d of age. The PRL levels were high at 15 and 28 d, declined at 40 d just after weaning and then rose slowly until 192 d of age. The number of LH pulses during 6 h was higher between 83 and 125 d than at the other periods. Magnitude of LH pulses was highest at 15 d, constant from 54 to 125 d, fell at 137 d and remained low until 192 d. Plasma FSH was high from 15 to 125 d, with a maximum at 54 d. It declined slowly until 168 d and did not change thereafter. Estrogen excretion was estimated from urine excretion of estrone (E1; conjugated plus nonconjugated E1) per 24 h from 40 d until puberty in three gilts and at 156 and 174 d in two other animals. The E1 excretion increased with age and four levels were described before peak values with the onset of first estrus. The first increase in E1 excretion occurred between 68 and 110 d, when antral follicles appeared in the ovaries. It was subsequent to the highest levels of FSH and concomitant with the increased frequency of LH pulses. The drop in levels of both gonadotropins after 125 d probably corresponded to the development of the negative feedback as a result of greater ovarian activity in these gilts.     

Effects of factors of nutrition and husbandry on the heat production of rats and broilers. 1. Heat production of growing broiler chicks kept in groups depending on the environmental temperature

In 2 experiments with young broiler chickens, origin Tetra B, heat production was measured in dependence on ambient temperature indirectly and with the gas exchange both over 24 h and in 20-minute periods beginning on their 5th day of live. The chickens, divided into 2 X 2 groups according to sex, were constantly kept in a climatic chamber changed in to a respiration chamber during the 8- or 11-week-long experiments. The maximum variation of the temperature was between 5 and 35 degrees C. In the periods of 24-h measurements over 4 days each, the ambient temperature was changed from day to day in steps of 5 degrees C. Heat production was influenced by the age of the chickens, energy intake and ambient temperature. The results of the measurements at the same age and the same energy intake and a temperature variation between 5 and 35 degrees C can well be described by polynomes of the 3rd degree up to the 8th week of live. The thermoregulatory conditioned heat production per 1 degree C below the critical temperature decreased with the age of the chickens. In the first few weeks of life it was 20 kJ, in the 6th and 7th weeks of life 10-15 kJ and then decreased to 4-5 kJ/kg life weight 0.75.d. degrees C. Based on the temperature of minimal heat production, the heat production of 16- to 30-day-old chickens increased to 60-80% at an ambient temperature of 5 degrees C; the metabolism of chickens older than 7 weeks was only increased by about 20%. For the first 2 weeks 35 degrees C were ascertained as critical temperature, for the 3rd to 6th weeks 30 degrees C and for the 7th and 8th weeks 25 degrees C.     

降钙素基因相关肽在鸭腔上囊胚胎及胚后发育过程中的表达

应用免疫组织化学技术研究降钙素基因相关肽在鸭腔上囊胚胎及胚后发育过程中的表达特征.结果显示,降钙素基因相关肽强阳性细胞出现于20 d胚龄至胚后14周龄的滤泡间上皮,20 d胚龄至胚后17周龄的小结相关上皮,新生雏至胚后14周龄的滤泡皮质,24 d胚龄至胚后14周龄的滤泡髓质,20 d胚龄至胚后14周龄的肌层和小动脉平滑肌.结果说明,降钙素基因相关肽表达于鸭腔上囊的不同部位及不同发育阶段;在腔上囊退化期,降钙素基因相关肽的表达表现出明显的变化特征,这可能是导致腔上囊退化的原因之一;滤泡间上皮与小结相关上皮在神经肽表达方面存在差异.     

Effect of age and physiological status on sperm storage 24 hours after artificial insemination in broiler breeder hens

1. Uterovaginal junction (UVJ) tissues were collected 24 h after artificial insemination (AI) from 85- and 125-week-old broiler breeder hens in three physiological states: laying hard shell eggs (HS), laying shell-less eggs (SL) and non-laying (NL). This was confirmed by egg production records and visual appraisal of the oviduct at the time of necropsy. 2. Three longitudinal sections of each UVJ were evaluated microscopically and sperm host glands (SHG) were scored in 5 categories: glandular morphology evident but not lumen present, basophilic stained epithelium and no spermatoza present, glands that contained one to five spermatozoa; glands that contained 6 to 20 spermatozoa and glands that contained more than 20 spermatozoa. 3. Laying hens (HS and SL) at 85 weeks of age had significantly more sperm host glands (SHG) containing spermatozoa than NL hens. At 125 weeks of age HS and SL hens had significantly more unscorable glands. 4. The only category that showed no difference between age and physiological status group was the empty category. No significant differences were observed for any gland category in 82- and 125-week-old NL hens. 5. A greater proportion of the 85-week-old group of HS and SL hens had more SHG containing spermatozoa and fewer unscorable glands that the 125-week-old birds. The only category that showed any difference within the SL group was the low category.     

Studies of the energy and protein requirements of the growing guinea-fowl.

1. Guinea-fowl of both sexes and female chickens were fed from 1 to 12 weeks on diets the energy concentration of which was constant at either 2-6, 2-9 or 3-2 Mcal/kg (10-8, 12-1 or 13-4 MJ/kg) while the calorie to protein ratios were changed, for some groups, from 124 to 157 or 200 at 4 and 8 weeks. 2. Guinea-fowl, but not chickens, were unable to overconsume when the protein concentration was low with the result that the body fat content was not reduced when the protein concentration was increased. 3. In the second trial the ME level of the diets was fixed at 12-6 MJ/kg while the protein content was varied, from 21 to 28% in the diets fed to 6 weeks of age and from 15 to 24% in those fed from 6 to 12 weeks. 4. It is concluded that for the growing guinea-fowl the diet should contain 12-6 MJ ME/kg, the protein concentration reducing from 24 to 26% in the period 0 to 4 weeks to 19 to 20% in the period 4 to 8 weeks and to 16% or less in the period 8 to 12 weeks.     

The Anatomy of the Cloacal Bursa (Bursa of Fabricius) in the Helmeted Guinea Fowl (Numida meleagris galeata)

The cloacal bursa (bursa of Fabricius) in the guinea fowls appeared either as an oval blind sac with a short thick stalk in one group or had a pointed cranial blind end with a slightly bulging middle part that was followed by a thick caudal stalk in the other group. Both groups of bursae originated from the proctodeal wall of the cloaca and were placed dorsal to the rectum. The average length of the bursa was 18 mm while the average width at die mid section was 15 mm. The internal surface showed about 12 – 14 primary folds. Histologically, the outline of the bursa was well established by day 18 of incubation. The primary folds had also been formed. Lymphocytes had already been encountered within the framework of the bursa at this day. The epithelium bordering the tunica propria was composed principally of two layers of cuboidal cells. Epithelial buds had also formed and some were already detached from the epithelial lining. The blood vessels present were positioned just beneath the outer covering. At day 19 of incubation, most of the epithelial buds had two layers of cells arranged in a circumscribed manner while a few had three layers of cells. Blood vessels had increased in number and were deeper placed inside the bursa than previously. At day 20, the cells of the upper layer of the epithelium were dorsoventrally flattened and stained paler than the cells of the lower layer. It was possible to distinguish the cortex from the medulla and the basement lining between both zones was distinct. Tiny vesicles within the cytoplasm of the epithelial cells at the mucosa and follicles were observed. Macrophges were also observed within the gland. At day 21, blood vessels were observed in the cortex of the follicles. The maximum number of primary folds (14) had been formed. At day 22, serveral follicles had severed connections with the mucosal epithelium. The mucosal lining had dropped to a single layer of cells in some areas. Goblet cells were observed amongst the mucosal cells. A plasma cell had first appeared. By day 25, dead cells had increased quite in number and there was also an increase in number of medium and small-sized lymphocytes within the gland. By day 26, the upper layer of the surface epithelium was composed primarily of tall columnar cells with numerous large vacuoles. Macrophages had suddenly increased within the thin interfollicu-lar spaces and most of them were crowded internally with various sizes of debris. By day one post-hatch, each fold was completely filled with follicles that were separated by thin connective tissue strands.     

Effects of vertically transferred 3,3',4,4',5-pentachlorobiphenyl on gene expression in the ovaries of immature Sprague-Dawley rats

We have previously shown that 3,3',4,4',5-pentachlorobiphenyl (PCB-126) vertically transferred from dams potentially exerts a direct effect on the ovaries of offspring and adversely affects female puberty. To investigate its toxicological targets in ovarian tissues, mRNAs encoding representative peptides that regulate follicular development in granulosa cells, theca cells, and oocytes were quantified using ovaries collected on postnatal days (PND) 5, 15, and 24 from the offspring of dams administered oral doses of 0, 1 or 3 microg/kg PCB-126 starting 2 weeks prior to mating and continuing until 20 days after delivery. Quantification using the real-time RT-PCR method revealed that PCB-126 lowered the amounts of mRNAs that encoded the inhibin alpha- and inhibin/activin beta A-subunits from PND 15 onwards; the amounts of mRNAs for inhibin/activin beta B-subunit, follicle-stimulating hormone (FSH) receptor, and aromatase on PND 15; and the amounts of luteinizing hormone receptor mRNA on PND 24 compared with those of the age-matched controls. In contrast, no differences were noted for mRNAs encoding c-kit, growth differentiation factor-9, bone morphogenetic protein-15, or kit ligand for any of the age groups examined. The serum FSH level on PND 24 was higher than that in the control. Since the earliest effects on the mRNAs in the rat ovaries were observed in those expressed in the granulosa cells of the growing follicles after the antral follicles had developed, molecules in granulosa cells but not in oocytes during the early stages of the antral follicles might be the primary targets of vertically transferred PCB-126.