Prenatal ethanol exposure delays the onset of spermatogenesis in the rat

Abstract

Background: During late prenatal and early postnatal life, the reproductive system in males undergoes an extensive series of physiological and morphological changes. Prenatal ethanol (EtOH) exposure has marked effects on the development of the reproductive system, with long-term effects on function in adulthood. The present study tested the hypothesis that prenatal EtOH exposure will delay the onset of spermatogenesis.

Methods: Development of the seminiferous tubules and the onset of spermatogenesis were examined utilizing a rat model of fetal alcohol spectrum disorder (FASD). Male offspring from ad libitum-fed control (C), pair-fed (PF), and EtOH-fed (prenatal alcohol exposure [PAE]) dams were terminated on postnatal (PN) days 5, 15, 18, 20, 25, 35, 45, and 55, to investigate morphological changes through morphometric analysis of the testes from early neonatal life through young adulthood.

Results: PAE males had lower relative (adjusted for body weight) testis weights compared with PF and/or C males from PN15 through puberty (PN45). In addition, fewer gonocytes (primordial germ cells) were located on the basal lamina on PN5, while more of those touching the basal lamina were dividing in PAE compared with PF and C males, suggesting delayed cell division and migration processes. As well, the percentage of tubules with open lumena was lower in PAE compared with PF and C males on PN18 and 20, and PAE males had fewer primary spermatocytes per tubule on PN18 and round spermatids per tubule on PN25 compared with C males. Finally, the percentage of tubules at stages VII and VIII, when mature spermatids move to the apex of the epithelium and are released, was lower in PAE compared with PF and/or C males in young adulthood (PN55).

Conclusions: Maternal EtOH consumption appears to delay both reproductive development and the onset of spermatogenesis in male offspring, with effects persisting at least until young adulthood.

Keywords: Fetal Alcohol Spectrum Disorder; Prenatal Ethanol Exposure; Reproductive Development; Spermatogenesis.

Figure 1

A. Gonocyte location in C (a), PF (b) and PAE (c) males at PN5 (N=6 for each prenatal treatment group). Scale bar = 50 µm Arrowhead points to gonocytes (touching the basal lamina in PF and C groups); B. Gonocyte proliferation status in C (a), PF (b) and PAE (c) males at PN5 (N=6 for each prenatal treatment group). Scale bar = 20 µm. Arrowhead points to dividing gonocytes (attached to the basal lamina in PAE, and located in the center in PF and C, males).

Figure 2

Seminiferous tubules with open lumena in C (a), PF (b) and PAE (c) males on PN18 (upper panel) and PN20 (lower panel) (N=6 for each prenatal treatment group at each age). Scale bar = 100 µm.

Figure 3

Primary spermatocytes on PN18 (upper panel) and round spermatids on PN25 (lower panel) in C (a), PF (b) and PAE (c) males (N=6 for each prenatal treatment group at each age). Scale bar = 50 µm. Upper panel: Arrow points to spermatogonia (in PAE males) that do not have condensed chromatin. Arrowhead points to primary spermatocytes (in PF and C males) that have condensed chromatin. Lower panel: Arrowhead points to round spermatids.

Figure 4

Junction complexes between Sertoli cells in the testes of C (a), PF (b) and PAE (c) males at PN18. Each of these low magnification images is a collage of two images joined at the thin white line. Junction complexes are identified by the presence of ectoplasmic specializations consisting of a layer of actin filaments (asterisks in insets) sandwiched between the plasma membrane and cisternae of endoplasmic reticulum (ER, in insets). Adhesion junctions often contain tight junctions identified by membrane “kisses” (arrowheads in insets) and gap junctions. When present, Junction complexes in the testes of PAE rats are situated near the center of the solid tubules and are short [arrow in (c)]. Junction complexes in C (a) and PF (b) males are numerous and form long linear tracts (arrows) near the middle of the developing epithelium, which now surrounds a lumen. Although membranes ‘kisses’ are occasionally observed within the Junction complexes in PAE rats, numerous tight junctions are obvious in PF and C rats. Scale bar = 1.0 µm. Scale bar in inset = 0.1 µm.