Differenzierung des Pansenepithels des Rindes während der intrauterinen Entwicklung

The prenatal development of the bovine ruminal epithelium was studied with light- and electronmicroscopical techniques. During the period of the nonstratified epithelium a pseudostratified epithelium is found in the dorso-cranial part, whereas the other areas possess a one-layered epithelium, which is, like the pseudostratified epithelium, transformed to a multilayered epithelium from the 7th week onwards. From the 9th week the period of the stratified epithelium starts with the formation of the stratum profundum and stratum superficiale. First signs of keratinization are seen in the superficial cells from 2.3 months onwards. With 4 months fetal cornified cells can be identified, with 5.5 months a single-layered stratum basale is seen on the differentiating papillar connective tissue, and the superficial cells are transformed to balloon-cells. In suprapapillar areas, a stratum spinosum is formed at the prenatal age of 7.5 months. During epitheliogenesis a horizontal and vertical differentiation of the cells can be observed. The first one includes the differentiation of undifferentiated, embryonal cells to the basal cells of the stratum profundum, the latter the development of the basal cells to spinous cells and then to fetal cornified and balloon-cells. The ultrastructural changes during the process of keratinization were especially considered.     

Zur Entwicklung des Pferdehodens

The aim of the study was to answer the open questions concerning the development of the horse's testis. This study revealed that the seminiferous tubules originate from the sex cords of the coelomic epithelium and Leydig cells from the proximal part of mesonephric nephrones, whereas the rete and the ductuli efferentes derive from intermediate and distal parts of the mesonephric tubules. During the development the Leydig cells undergo an enormous proliferation due to the PMSG secretion in the mare. The proliferation of these cells prevent the deep penetration of the rete into the medulla and is therefore the reason for the reduced extension of the rete and mediastinum testis in the stallion, although 80% of these cells degenerate in the last third of pregnancy. The growth of the seminiferous tubules during sexual maturity reduces the rete to the extremitas capitata of the testis.     

Zur Entwicklung der Gelenkhöhle des Hufgelenks an der Beckengliedmasse beim Fetus und Fohlen im Vergleich zum adulten Pferd

Ten horses, younger than 1 year, were used to investigate the articulatio interphalangea distalis of the pelvic limb. The expansion of the dorsal recess was compared to those of adult horses. The recessus dorsalis always formed a shape like the letter ‘m’ or like a triangle with oblique angles. Consequently the great proximo-distal expansion on the medial side of the dorsal recess very probably has nothing to do with the age of horses.     

Über die frühfetale Entwicklung der Dünndarm-Mukosa des Rindes (Bos primigenius taurus).

The development of the bovine small intestine was examined in 24 embryos and fetuses by light microscopic, scanning and transmission electron microscopic methods. Special reference was paid to the genesis of the epithelium and particularly of the villi intestinales. The primitive intestine consists of one layer of epithelial cells surrounded by mesenchym and tunica serosa. The fetal intestine (up to the 24th week of gestation) shows all the morphologic structures of the adult. In small intestine the development of cryptae and villi intestinales starts before the 7th week of gestation and progresses with a proximo-distal gradient. Epithelial proliferation that gives rise to primary epithelial villi makes epithelium become temporarily stratified. Finger-like secondary villi develop by proliferation of the mesenchym. In addition to this process mucosal folds occur in duodenum giving rise to villi by segmentation. At the same time the differentiation of epithelium starts. The fetal small intestine, like many other fetal tissues displays masses of glycogen.     

Histochemische Untersuchungen an den Mukosubstanzen der Blinddarm-Becherzellen des Rindes

The mucins of the goblet cells, according to their different chemical compounds, are differently stained in the various regions of the intestinal tract. Several histochemical techniques are applied to sections from the bovine cecum of 5 fetusses and 4 adults to study distribution patterns of the different types of mucosubstances in this species. The results obtained show that the crypt goblet cells produce both orthohromatic neutral mucins and orthochromatic sulfo- and sialomucins irregularly distributed.