Steuerung und Beeinflussung der Samenbildungsprozesse

[Histomorphometric and histological investigations of the morphometric effects of furazolidone on spermatogenesis in mature rats]

The antispermatongenic effects of furazolidone on the testes of mature Wistar rats were investigated using histological and morphometric methods. The sections showed a varying degree of depopulation of the germinal epithelium, a shrinking and a deformation of the Tubuli contorti, and an enlargement of the intertubular lymphatic sinuses. The strain led to a standstill in the spermatogenesis at the primary-spermatocyte stage. After administering furazolidone, the following results could be seen: a weight loss of up to 42.1% and a decrease in testes volume by up to 30.2%; a decrease in the volume of the nuclei of the Leydig-cells by up to 51.6%; a reduction in the diameter, perimeter and area covered by Tubuli seminiferi contorti of up to 33.5%, 30.8%, and 53.4%, respectively; an increase in the number of Tubuli seminiferi contorti per mm2 by up to 44.8%; a decrease in the percentage of Tubuli seminiferi contorti of the total testes tissue by up to 39.1%.

Regularities and irregularities in the structure of the seminiferous epithelium in the domestic fowl (Gallus domesticus). II. Co-ordination between germ cell associations

It was investigated in the domestic fowl, whether a mechanism for a synchronous start of the proliferation of the differentiating spermatogonia in a transversely cut seminiferous tubule (called the "co-ordination" between germ cell association) operates effectively in this species. A trapezoid-shaped cellular association demarcated by two perpendiculars from the tubular lumen to the basement membrane was the unit of observation (provisionally called a "column" Each column is composed of a bundle of elongate spermatids and the neighbouring, various types of germ cells). The extent of closeness of the co-ordination was examined in a total of 2,650 columns, based on the continuity of the spermiogenic step-number of the youngest generation of spermatids within adjacent columns. In no case did all columns in a tubular cross section show the same-step spermatids. In most cases (50.2% of 2,650 columns), the same number was kept in only 2 to 6 adjacent columns. The arrangement of different but consecutive numbers (e.g., 1-2-3 or 1-2-1) was observed in a total of 882 columns. The co-ordination mechanism, therefore, is considered to work, albeit incomplete, among a limited number of adjacent columns in this species.

Relative positions of the spermatogenic stages in the mouse testis: morphological evidences for their non-randomized adjacencies

The topographical distribution pattern of the stages of the murine seminiferous epithelium cycle was investigated. PAS-hematoxylin stained testicular sections from adult mice representative of the apical, equatorial and caudal region of both testes, were used. The relative frequencies (RF) of the stages of the seminiferous epithelium cycle was estimated on the basis of more than 10,000 cross-sectioned seminiferous tubules identified according to the criteria of Leblond and Clermont (1952). It was found that in the testicular sections the stages of adjacent seminiferous tubules are not distributed randomly. The comparison of the RF of the stages (calculated over all the testicular sections) with the RF of the stages that are adjacent to a given seminiferous tubule stage suggests a clustered occurrence of numerically identical stages. These comparisons very often show statistically significant differences. The finding of such associations among adjacent segments of seminiferous tubules (stages) suggest the existence of an ordered distribution of the seminiferous tubules inside the testis possibly controlled by substances with local control capacity of spermatogenesis. On the basis of the findings here presented, it is suggested an interpretation of the phenomenon of modulations of the waves of the seminiferous epithelium.

Evidence of a wave of spermatogenesis in human testis

The present report documents the strikingly regular appearance and arrangement of the spermatogenic stages i seminiferous tubules of two aged males. Analysis of the pattern of distribution of the stages in seminiferous tubules of two aged males. Analysis of the pattern of distribution of the stages in two-dimensional maps of the seminiferous tubules revealed the presence of helically arranged sequences of stages. Similar results were obtained from testicular tissue of a younger patient. The present findings indicate the existence of a spermatogenic wave in human seminiferous tubules. It is suggested that the particular pattern of the human seminiferous epithelium may emerge from a specific mode of spermatogonial proliferation and renewal.