Spermatogenesis in the dog

Abstract

The cycle of the seminiferous epithelium of the dog was divided into eight stages, using as criteria the shape of the spermatid nucleus, the location of spermatids and spermatozoa in regard to the basement membrane, the presence of meiotic figures and the release of spermatozoa from the lumen of the tubule. Based upon these criteria, a modification of the eight-stage system of classification of the cycle of the seminiferous epithelium was developed. Cell populations making up each stage are described. The relative frequencies of stages 1 through 8 were 21.9, 12.7, 2.8, 11.5, 8.3, 15.4, 13.3 and 14.0%, respectively. The duration of one cycle of the seminiferous epithelium was 13.6 days (SE -t. 0.7), as determined from cells labeled by tritiated thymidine. The absolute durations of stages 1 through 8 were 3.0, 1.7, 0.4, 1.6, 1 .l, 2.1, 1.8 and 1.9 days, respectively. The life span of primary spermatocytes was 20.9 days, of secondary spermatocytes 0.5 days, spermatids with round nuclei 10.5 days, spermatids with elongated nuclei up to the time they are released into the lumen, 10.6 days. Counts of the different types of spermatogenic cells in tubular cross sections revealed little or no germ cell degeneration during the two maturation divisions.The mitotic and meiotic divisions and associated processes by which spermatogonia are transformed into spermatids and by spermiogenesis into spermatozoa occur in an organized manner in mammals. Several germ cell generations develop simultaneously, and this leads to fixed cellular associations in the sexually mature male. 14s a result, at any given point of seminiferous epithelium a series of cellular associations or stages follow one another with passage of time. A complete series of stages up to the reappearance of the first one at a given point constitute the cycle of the seminiferous epithelium '50; Leblond and Clermont, '52; Ortavant, Courot and :Hochereau, '69).Despite intensive use of the dog for research, including studies pertaining to :reproduction, there seems to be little detailed quantitative information on spermatogenesis in this species. Bascom and Osterud ('25) studied the size and proportion of the seminiferous tubules. Malone ('18) and Minouchi ('28) described nuclear cytology and chromosomal behavior ANAT. REC., 173: 341-352.

Inhibition of Canine Spermatogonial Mitosis with Follicle Regulatory Protein

“…To answer this question, we quantitated the corresponding type A and type B spermatognia. The number of type B spermatogonia at stage 7 in the control group was almost identical to that reported by Foote et al [22]. The ratio of type B to type A spermatogonia @/A) in both FRP-treated and control groups rapidly increased at stages 6-7 and decreased during stages 7 and 8.…”

Quantitative Aspects of Water Buffalo (Bubalus bubalis) Spermatogenesis.

“…The second way to divide the seminiferous epithelial cycle uses cellular associations of defined composition in conjunction with variations in shape and localization of spermatids. This method has been established for a number of domestic animals (CLERMONT, 1972;FOOTE et al, 1972;SWIERSTRA et al, 1974;EKSTEDT et al, 1986), leads to a restricted number of stages (mostly 8), and is especially well suited for comparative and quantitative studies. According to this latter method the spermatogenic cycle in the buffalo seminiferous epithelium is divided into 8 stages with accomplished spermiation as the demarcation between the two cycles, as has been proposed by EKSTEDT et al (1986) for the bovine seminiferous epithelium.…”

Therapeutic Effect of Aromatase Inhibitor in Two Azoospermic Dogs with High Plasma Estradiol-17β Levels

“…of spermatogenesis by the increased T volume in the testes. The duration of spermatogenesis in the dog has been reported to be 54.4 days [5], and the duration of transit of sperm through the epididymis in many mammalian species is 8-14 days [14]. Therefore it is assumed that a small number of sperm had already been presented in a few seminiferous tubules before AI treatment.…”