Continual maintenance of the blood-testis barrier during spermatogenesis: the intermediate compartment theory revisited

Tight junctions occur between the lateral processes of neighboring Sertoli cells that divide the seminiferous epithelium into two compartments: basal and adluminal compartments. These tight junctions constitute the blood-testis barrier (BTB). The established theory that the BTB must open when spermatocytes translocate from the basal compartment to the adluminal compartment is marked by one contradiction, that is, normal spermatogenesis occurs in the testis because the BTB is expected to constantly seclude the adluminal compartment from the basal compartment in order to protect haploid germ cells from the autoimmune system. Subsequently, another concept was proposed in which two BTBs divide the seminiferous epithelium into three compartments: basal, intermediate and adluminal compartments. It has been suggested that the transition from the basal region to the adluminal region without the BTB open occurs through the agency of a short-lived intermediate compartment embodying some primary spermatocytes. In contrast, the results of recent findings in the molecular architecture of the BTB suggest that the BTB in the seminiferous epithelium must "open". In this paper, I re-examine the BTBs of boar and experimental cryptorchid mouse testes by transmission electron microscope (TEM). TEM analysis showed that an atypical basal compartment existed in the thin seminiferous epithelium of 14-day post-cryptorchid mice testes. In developmental boar testes, ectoplasmic specialization (ES) of the seminiferous epithelium showed dynamic behavior. The intermediate compartment was clearly observed between the basal and adluminal compartments of the mature boar seminiferous epithelium. ESs were observed between Sertoli cells and spermatids at all developmental stages, including early, late and mature. Furthermore, ESs were situated on the apical surface of the seminiferous epithelium. From these results, I propose that the BTB is continually maintained during spermatogenesis and suggest a model of ES circulation in the seminiferous epithelium.     

The fine structure of the pores in the shell of the hen's egg

1. No fibrous or crystalline material was present in the lumen of pore canals which were exposed by radial fracture and examined with a scanning electron microscope.

2. The walls of the canals were rough, but they did not have a characteristic ultrastructure.

3. The campanulate outer orifice of the pores was plugged with cuticle in which radial cracks formed channels through which the respiratory gases presumably diffuse.     

The fine structure of the Harderian gland in the ostrich (Struthio camelus)

The Harderian gland of the ostrich (Struthio camelus) is a tubuloalveolar gland containing holocrine secreting epithelial cells. The gland epithelium is composed of two different cell types, which can be classified as type I and type II. These cells contain dense secretory vesicles in their cytoplasm and they are connected laterally with desmosomes. At the basal site of these cells, myoepithelial cells are present. Plasma cells are observed in the subepithelial region of the gland. In the interlobular trabeculae, forming the gland stroma, fibroblasts, blood vessels and nerve fibres are included. Another important finding in the ostrich Harderian gland is the presence of homogeneous material.     

特种野母猪适宜日粮结构与能量水平的研究

试验研究不同日粮结构和能量水平对后备期特种野母猪饲料养分消化率、血清生化指标的影响。通过采用2(日粮结构)×4(能量水平)因子设计,选用后备特种野母猪32头随机分为8组",玉米-豆粕"型和"40%的稻谷-玉米-豆粕"型日粮各设4个能量水平。结果表明:①养分表观消化率:不同日粮结构对各营养物质表观消化率的影响未达显著水平(P>0.05)。不同能量水平对试验猪只总能、粗蛋白、干物质的表观消化率的影响显著(P<0.05),对粗灰分的表观消化率影响不显著(P>0.05)。②生化指标:不同日粮结构对各生化指标影响均不显著(P>0.05)。不同能量水平对血清TP、血清Alb、血清Glo的影响达到了显著水平(P<0.05)。结论:后备期特种野母猪最适宜的日粮结构为"40%的稻谷-玉米-豆粕"型日粮,消化能为13.00 MJ/kg。     

The fine structure of the nucleus of the hypoglossal nerve of sheep and goats]

In the small domesticated ruminants the nucleus of the hypoglossal nerve is situated in close relationship to the median line in the middle of the elongated medulla. The nucleus is divided by the obex into a rostral and a caudal portion. In the sheep, four distinct subnuclei can be recognized, whereas in the dwarf goat great variations in the arrangement of cell groups exists. In both animals large and medium sized neurons are observed. The large neurons are characterized by densely packed small organelles. The medium sized neurons vary between a pale and an electron dense type. According to the size and morphology of the vesicles three types of synaptic contacts can be differentiated. Synapses of type 2 contain clear round and flattened vesicles and are partially accompanied by subsurface cisterns.     

Intestinal villi structure during the development of pig and wild boar crossbreed neonates

Modification in mucosa structure can be used to evaluate intestinal function during the development. Our study aimed to compare the postnatal gut mucosa structure in Polish landrace/Pietrain (PP) and Duroc/Hampshire/wild boar (DHW) crossbreed piglets using scanning electron microscopy. Small intestinal mucosa showed a number of changes characteristic for PP and DHW pigs involving the modification of villi shape, disappearance of transversal furrows, formation of extrusion zones and presence of apoptotic cell packets.     

猪冷冻精液的研究

本试验以甘油、乙二醇为抗冻剂，并添加ATP或安息香酸咖啡因，以解冻后精子活力、顶体完整率、顶体膨胀率、顶体破损率、尾部畸形率和在37℃下的存活时间几个重要评定指标为依据，筛选了几种猪颗粒冻精的冷冻稀释液配方，并优化了其冷冻程序。结果表明，与对照组相比，在冷冻液中添加0．1mg／ml的ATP或2mg／ml的安息香酸咖啡因都能显著提高解冻后精子活力(分别提高0．13和0．18)，降低顶体膨胀率(两者都将近降低了11％)，并能延长其存活时间(分别延长10．5h和11．8h)；甘油和乙二醇两种抗冻剂配合使用，将显著提高冻后精子的活力与存活时间，其较优混合量为甘油3％，乙二醇0．5％。     

猪精液冷冻保存研究进展

根据国内外的研究进展,本文简要阐述了猪精液冷冻保存的机理和操作方法,对影响猪冷冻精液质量的因素进行了分析,同时指出了目前在猪精液冷冻保存技术的理论和实践中存在的问题,并提出了该技术中需要解决的问题和展望。     

The lysine requirement of the growing boar versus barrow

Five experiments were conducted to determine if boars and barrows differ in the level of dietary lysine required to maximize growth rate, efficiency of feed utilization, carcass leanness and N retention. In Exp. 1, 48 boars and 48 barrows were fed fortified corn-soybean meal diets calculated to contain 14 (grower) and 12% protein (finisher) and supplemented with 0, .15 or .30% lysine from 27 to 105 kg body weight. The basal diets analyzed .60 and .47% lysine, respectively. Linear improvements in feed/gain (P less than .01), backfat thickness (P less than .10), longissimus muscle area (P less than .01), and ham-loin (P less than .05) and lean cuts percentage (P less than .1) were observed in boars as dietary lysine increased. In barrows, however, growth rate, feed:gain ratio and carcass characteristics (except longissimus muscle area) were not significantly affected by dietary lysine level. In Exp. 2, 18 boars and 18 barrows initially averaging 64 kg body weight were fed a 12% protein diet (.47% lysine) supplemented with 0, .15 or .30% lysine. Linear (P less than .05) increases in N retention occurred in boars, but not barrows, as dietary lysine was increased. In Exp. 3 and 4, 140 boars (34 to 103 kg) were fed a 14-12% protein sequence (analyzed .61 and .48% lysine) supplemented with 0, .1, .2, .3 or .4% lysine. In Exp. 5, 60 boars (23 to 103 kg) were fed a 16-14% protein sequence (analyzed .83 and .68% lysine) supplemented with 0, .075, .15 or .225% lysine.(ABSTRACT TRUNCATED AT 250 WORDS)