Effect of Stress on the Testis and the Ovary in Albino Rats in Prenatal and Postnatal Periods (Histological and Histochemical Study)

Abstract

The present study investigated and compared the effect of noise stress exposure on the testis and the ovary of albino rats at three critical periods of life; the prenatal, pre-pubertal and adult stages. The aim was to reveal the most susceptible period of lifetime during which these organs are prone to injury. Seventy two albino rats (36 males and 36 females) of Wistar strain were used in the study. The experimental groups were exposed to noise at an intensity of 100 dB for a period of 6 hours daily from 8am to 2pm o’clock for all groups. Pregnant mothers were exposed to noise stress for 12 days (from day 8 – day 20 of gestation) then fetuses were extracted while pre-pubertal (aged 3weeks) and adult (aged 3 months) rats were exposed to noise stress for 4 weeks. Rats were assigned to 12 groups (each containing 6 rats); both control and experimental. At the end of the experiment, all animals; control and those exposed to noise (20 days old fetuses, 7 weeks old rats and 4 months old rats) were sacrificed using over dose of ether inhalation. The testes and ovaries of all rats were collected. The specimens were processed for paraffin block embedding and stained with standard histological stains (Hx&E, PAS and Masson’s Trichrome) for light microscopic examination. Immunohistochemical staining for apoptosis was performed on paraffin sections utilizing TUNEL assay. Histomorphometric analysis was performed utilizing image analysis software and results were subjected to statistical analysis using ANOVA test. Regarding the testis, the three age control groups showed histological differences. The tunica albuginea increased in thickness in contrast to tunica vascuolsa which diminished in thickness as age advanced. Size of the seminiferous tubules increased with age. Regarding the germinal epithelium, the testes of 20 days old rat fetuses was composed only of two types of cells; the gonocytes and the supporting cells. In the 7 weeks old rats, the germinal epithelium was formed of several cell types; spermatogonia, the spermatocytes, the round immature spermatids. Few elongated mature spermatids were detected in this age group. Regarding the 4 months old group, the germinal epithelium was formed of spermatogonia, spermatocytes, round spermatids and elongated spermatids, arranged in that order from the basal compartment to the adluminal compartment. Sertoli cells were more detected in the adult group compared to the 7 weeks old rats. The interstitial cells of Leydig increased in number as age advanced. Examination of the testes of 20 days old albino rat fetuses whose mothers were exposed to noise revealed that the tunica albuginea was apparently thicker than the control group and the tunica vasculosa was also formed of less densely arranged loose connective tissue compared to the control group. Seminiferous follicles were gathered into clusters and their size decreased compared to the control group. The supporting cells were detached from the basement membrane and were closely packed with pyknotic nuclei. The gonocytes also showed pyknotic nuclei with vacuolated cytoplasm compared to the control group. Examination of testes of the 7 weeks old albino rats which were exposed to noise, at the age of 3 weeks for one month, showed the presence of localized thickening of tunica albuginea and increased thickness of tunica vasculosa. Size of seminiferous tubules was smaller compared to the control group. Some areas showed wide separation of the tubules from the capsule. Most of the tubules showed rupture of their basement membranes. The spermatogenic cells lining the tubules showed pyknotic nuclei with massive cytoplasmic vacuolation while others were exfoliated into the lumen. Some Sertoli cells also showed pale staining of their nuclei. Interstitial cells of Leydig had dark nucleus with presence of congested blood vessels in some interstitial tissue spaces. The most characteristics observation was retardation of development of seminiferous tubules. This could be detected by the absence of mature spermatids which were detected in the control group. Examination of testes of 4 months old albino rats exposed to noise revealed relative thinning of tunica albuginea and thickening with congestion of blood vessels in tunica vascuolsa compared to control group. The seminiferous tubules were reduced in size. Various forms of affection of the spermatogenic cells lining the seminiferous tubules were seen ranging from extreme thinning out of the epithelium in some locations to patches of focal degeneration or exfoliation into the tubular lumen. Spermatogonia, spermatocytes and spermatids showed fusion of their cell membranes, cytoplasmic vacuolation, nuclear disintegration and cellular necrosis. Some Sertoli cells also showed faint stained degenerated nuclei while others were unaffected. Most of the interstitial cells of Leydig showed faint staining of their nuclei. Few of them showed small dark nuclei.