SUMMARY OF EGG AND SPERM DEVELOPMENT 



171 



Egg (in Oogenesis) 



Sperm (in Spermatogenesis) 



2. Cytoplasmic maturation 

 This involves: 



a. Polarization of cytoplasmic materials 

 and the nucleus in relation to the fu- 

 ture maturation phenomena; the nu- 

 cleus becomes displaced toward one 

 pole, the animal pole, and the yolk, 

 and other cytoplasmic materials; in 

 many eggs becomes displaced toward 

 the opposite or vegetal pole 



b. Formation of deutoplasm or stored 

 food material, varying greatly in 

 amount in different animal species. 

 The deutoplasm is composed of 

 fats, carbohydrates, and protein sub- 

 stances 



2. Cytoplasmic maturation 

 This involves: 



a. Polarization of nucleus and cytoplas- 

 mic materials along an elongated 

 antero-posterior axis, with the head, 

 neck, middle piece, and tail occupy- 

 ing specific regions along this axis. 

 The nucleus occupies a considerable 

 portion of the anterior region or head 



b. Little food substances stored within 

 cytoplasm; food reserve in seminal 

 fluid 



c. Cytoplasm increased in amount; for- 

 mation of basic organ-forming areas 

 or cytoplasmic stuffs from which the 

 future embryo arises 



d. Formation of primary embryonic 

 membranes 



3. Physiological maturation or the devel- 

 opment of a fertilizable stage 



This involves: 



a. Formation of an organization which 

 when stimulated by external influ- 

 ences initiates and carries on the 

 processes necessary for normal em- 

 bryonic development 



b. Acquisition of ability to enter into 

 a developmental union with a sperm 



c. Development of ability to form and 

 secrete gynogamic substances which 

 aid in the fertilization process. (See 

 Chap. 5) 



d. Assumption of an inhibited or dor- 

 mant condition during which meta- 

 bolic processes proceed slowly in an- 

 ticipation of the fertilization event 



c. Discarding of a considerable amount 

 of cytoplasm, some Golgi elements 

 and mitochondria. Retention of some 

 Golgi elements, centrioles, mitochon- 

 dria, etc. 



d. No specific membranes formed 

 around sperm, although elaborate 

 membranes for motile purposes are 

 formed in some sperm 



3. Physiological maturation or the devel- 

 opment of the ability to contact and 

 fertilize the egg 



This involves: 



a. Development of an organization 

 which, when stimulated by proper 

 external substances, responds by a 

 directed movement resulting in loco- 

 motion; also capable of being at- 

 tracted by egg substances 



b. Acquisition of ability to fertilize, i.e., 

 to enter into a developmental union 

 with an egg or oocyte 



c. Acquisition of ability to produce and 

 secrete androgamic substances which 

 aid in the fertilization process 



d. Assumption of an active metabolic 

 state 



