208 STUDENTS HISTOLOGY 



10. Ova in the early stages of development from primordial 

 cells, with granular vesicles. 



11. Instances of development of two, possibly three, ova 

 in a single follicle. 



12. Large blood-capillary supply of cortex, vessels generally 

 parallel with the chains of follicles. 



THE MA MM ART GLAND 



The mammary gland consists of acini lined by epithelial cells. 

 The acini are grouped into lobules and lobes. There is an abun- 



FIG. 130. MAMMARY GLAND OP THE DOG. TRANVERSE SECTION OF AN ACINUS 

 IN THE EARLY STAGES OF FAT FORMATION. (HEIDENHAIN.) 



dant framework of fibrous and adipose tissue. The ducts are lined 

 by columnar epithelium, and open at the nipple. The lobules and 

 acini of the resting gland are small. During activity the acini are 

 lined by low cubical epithelial cells resting on a basement mem- 



FIG. 131. MAMMARY GLAND OF THE DOG AT THE HEIGHT OF ACTIVITY. 

 (HEIDENHAIN.) 



brane. Globules of oil form within these cells, and are discharged, 

 making the oil -globules of the milk. 



The secretion of the gland during the first few days of activity 

 contains numerous cells in which drops of oil are present, the 

 colostrum-corpuscles. Sections of the resting and active mam- 

 mary gland of the dog may be studied with advantage. 



