Postnatal differentiation of leydig cells in the rabbit testis

Abstract

After the gradual disappearance of fetal Leydig cells in the first week after birth, the interstitial tissue of the rabbit testis is composed principally of undifferentiated mesenchymal cells between one and five weeks of age. Also present during this time are scattered partially differentiated cells with oval-shaped nuclei, prominent nucleoli and abundant cytoplasm. These cells exhibit some of the cytoplasmic features of steroid-secreting cells, but extensive development of smooth endoplasmic reticulum and the grouped perivascular arrangement of characteristic of fully differentiated Leydig cells are not present. The latter features appear at five weeks of age, indicating the formation of mature Leydig cells at that time. By seven weeks, the bulk of the interstitial tissue consists of Leydig cell aggregates, typical of the appearance in adult testis. Since spermatogonial mitoses first appear at seven to eight weeks of age, the findings indicate that Leydig cell differentiation precedes the onset of spermatogenesis.

Impact of environmental pollutants on the male: Effects on germ cell differentiation

“…Furthermore, use of rabbits (in contrast to rodents) facilitates multiple evaluations of seminal quality and sexual capacity (Foote and Berndtson, 1992). Chronology of testicular development (Gondos et al, 1973;1976) and methods for critical evaluation of reproductive function (Amann 1982) for this species are well characterized and documented.…”

“…Concomitantly, pre-Sertoli cells in the seminiferous epithelium proliferate and then acquire morphological features characteristic of differentiated Sertoli cells. Throughout the interval from wk 7 to 8 through wk 12 to 15, Sertoli cells are closely associated with adjacent germ cells (Gondos et al, 1976). With regard to germ cells, during late gestation and the early infancy, the seminiferous epithelium contains only gonocytes and then prespermatogonia.…”

“…Adolescent exposure encompassed the infantile period of functional differentiation of testis -differentiation of Leydig cells and Sertoli cells, onset of spermatocytogenesis, and initiation of puberty (Gondos et al, 1976). Post-pubertal exposure encompassed at least six cycles of the seminiferous epithelium, which has been suggested to be optimal to evaluate the effects of xenobiotics on gametogenesis in adult rabbits (Amann, 1982).…”

Relationships between Leydig cell morphometry and plasma testosterone during postnatal development of the monkey, Macaca fascicularis

“…Postnatal variations in Leydig cell number and/or size are parallel to the timing of testosterone secretion in rabbit (Gondos et a/., 1976(Gondos et a/., , 1977 and boar (MeusyDessolle, 1975 ; Van Straaten and Wensing, 1978 ;Peyrat et al, 1981 ;Allrich et a/., 1983). Ultrastructural changes in the Leydig cells of rat (Lording and de Kretser, 1972), rabbit (Gondos et al, 1976) and the monkey, Cercopithecus aethiops , suggest that the ability to synthesize testosterone may vary during postnatal development, but distinct correlations between these two processes were not demonstrated. Only morphometric analysis has been able to show that the ability of the testis to synthesize testosterone is correlated with the amount of smooth endoplasmic reticulum (SER) of the Leydig cells (Zirkin et a / ., 1980 ;Ewing et al, 1983).…”

Developmental and regressive changes in the testes of the Himalayan rabbit

“…After the gradual disappearance of fetal Leydig cells during the first week, the formation of mature Leydig cells appears at 5 weeks of age (Gondos et al, 1976). Thereafter, the peri pubertal phase starts with a striking increase in testosterone and FSH levels, and an acceleration of testicular growth.…”