Holarctic Marmots as a factor of Biodiversity.
Rumiantsev V.Yu;, Nikol'skii A.A. & Brandler O.V. eds.,
Abstracts, 3d Conference on Marmots (Cheboksary, Russia, 25-30 August 1997),
Moscow ABF 1997, 216p. : 196.


FACTORS AND CONTROL MECHANISM IN MARMOTS' TESTICLE FUNCTIONAL ACTIVITY (ENDOCRINE, PARACRINE, AUTOCRINE ASPECTS)


A.A. Stadnikov*, N.N. Shevljuk*, V.N. Rudy,** L.A. Lopatinskaya, O.Ya. Nikolaeva

* State Pedagogical University
** State Medicine Academy, Orenburg, Russia


By present many factors and mechanisms controlling seasonal changing of reproductive activity in marmots are unknown. As marmot mating, pregnancy and even early period of lactation take place inside the burrows, immediately following hibernation and before emerging on the surface (Bibikov, 1989; Mashkin, 1996), then duration of photoperiod can hardly influence seasonal fluctuation of marmot reproductive activity in late winter after hibernation.

Thus, perhaps the main factor, trigging mechanism of testicle endocrine and spermatogenic functions activating after hibernation, is endogenic circannual rhythm for reproductive system.

The following facts indicate importance of paracrine interactions for regulation of endocrine and germinative testicle functions: 1) asynchronous start of spermatogenesis in curved tubules, as well as asynchronous regression of this activity; 2) structural heteromorhism of interstitial endocrinocytes, located around tubules with different condition of spermatogenic epithelium. The largest endocrinocytes are likely to locate around the tubules, in which meiosis goes, and also around the tubules with signs of destruction in spermatogenic epithelium.

Probable role of autocrine mechanisms in regulation of histophysiology of interstitial endocrinocytes is proved by different morpho-functional parameters of endocrinocites, located around the tubules with similar condition of spermatogenic epithelium.

Mechanisms of spermatogenesis suppression, observed in some mature males in breeding time, need further research. Available literature data, concerning problems of social contraception in populations of particular animals, are based mainly on external examination of sex gland condition (mass, length, width, consistence) and contain no information on histology of testicles and central control endocrine organs (hypothalamus, hypophysis, epiphysis). We found no literature data on the quota of male bobacs of the total mature animals number, which annually participate in breeding. By data of V.I. Mashkin (1996) quota of breeding females comprises 32.9 0.53% for Kazakhstan bobac subspecies and 57.5 1.42% - for European subspecies.

According to our data, obtained on the base of bobac study in Orenburg Region, quota of males which could participate in breeding (by microscopic examination of sex glands) was 58.3 4.1%. And the rate of depression of testicle endocrine and germinative functions did not always correlate with marmot fatness.

Thus, reported information indicates the complex character of interactions of central and local factors in regulation of reproductive system in marmot males. So, complex study of the structure of sex glands and central regulating organs in marmots seems very challenging.


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