Publisher Summary This chapter discusses the development of follicles in the mammalian ovary. The unresolved issues in follicular development are focused. Folliculogenesis culminates in the production of fully ripe, preovulatory follicles visible to the naked eye as large bulges on the surface of the ovary. Each ripe follicle contains thousands of highly differentiated cells. This complex, functional miniature organ arises from the handful of cells that constitute a simple primordial follicle, a structure so small that it is invisible at the lower magnifications of a light microscope. All regulatory influences can only permit or prevent cells from completing the full maturation process; they cannot change the course of differentiation. A plethora of modulating influences act as permissive inducers, impeding or propelling the committed follicular cells through the process of clonal expansion. As each follicle progresses through its program of limited clonal expansion and maturation, its cells proliferate more and more rapidly. With every passing generation, the proliferative potential of the granulosa and theca cells continues to diminish, while the state of maturation increases.

Development of Follicles in the Mammalian Ovary

Physiological changes at parturition and their relationship to metabolic disorders.

According to much evolutionary thinking, males of promiscuous species are able to produce quantities of sperm that are virtually unlimited and should be selected to mate indiscriminately with all available females. However, sperm are generally delivered in batches (ejaculates or spermatophores) that may include many millions of gametes. Males are limited with respect to the number of ejaculates they can deliver and the time required to restore depleted reserves. Because ejaculates are a limited resource, prudence would be expected in the allocation of ejaculates to females. Among the forces acting to limit the number of females with which a promiscuous male mates are high pregnancy initiation requirements, sperm competition, female choice and control, and the costs and risks of searching. Optimal strategies for ejaculate allocation will vary with the operational sex ratio. Males can and do discriminate among females as potential mating partners. The problems of limited ejaculatory capacity and male choice...

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Ejaculate Cost and Male Choice

Effects of heat stress on the welfare of extensively managed domestic ruminants

All processes of life, all physiological events, do work and expend energy. A continuing supply of energy is necessary for an animal to live. One of the primary means by which the environment influences animals is through the exchange of energy. If the animal takes in more energy than it gives out it will get warmer, overheat and perish. If the animal loses more energy than it gains it will cool and not survive. An animal may warm or cool for a limited period of time, but on the average, over an extended period of time, an animal must be in energy balance with its environment: The mobility of most animals permits them to seek the environment most compatible with their physiological requirements for energy. The factors of the environment which are primarily responsible for energy flow to an animal are several, e.g. radiation (sunlight, skylight, and radiant heat), air temperature, wind, and humidity. There are other environmental factors, such as the gravitational, electrical, or magnetic fields, which might determine energy flow between animals and environment but may be ignored as generally not significant to the energy budget of an animal. The microclimate around an animal is thought of as a four dimensional space in which the four independent variables-radiation, wind, air temperature, and humidity-are acting simultaneously and are each time dependent. The exchange of energy between an animal and its environment affects the body temperature of the aimal. The body temperature is considered here as a dependent variable. The rate of moisture loss by the animal is in part determined by environmental

Thermodynamic equilibria of animals with environment

Reproduction in farm animals , Reproduction in farm animals , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Reproduction in farm animals

The behaviour of domestic animals

Reproduction and Breeding Techniques for Laboratory Animals

Human semen and fertility regulation in men , Human semen and fertility regulation in men , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

E. S. E. Hafez

Papers

Reproduction in farm animals

The behaviour of domestic animals

Reproduction and Breeding Techniques for Laboratory Animals

Human semen and fertility regulation in men

Adaptation of Domestic Animals