THE LACTEAL GLANDS. 



663 



true gland-vesicles. In rave, but well-established instances, the glands, 

 even in the male, have become so much developed as to be capable of 

 secreting milk. 



§ 211. Physiological remarks. — The lacteal gland, in its develop- 

 ment, follows the same course as the other cutaneous glands, and is, 

 as I find ("Mittheil. d. ZUrcher nat. Gesells.," 1850, No. 41) in ac- 

 cordance with Langer (1. c), originally (in the fourth to the fifth 

 month) nothing but a solid papillary projection of the mucous layer of 

 the epidermis, which is invested by a layer of denser dermal tissue 

 (Fig. 273, ^). In the sixth to the seventh 

 month, it throw^s out a certain number of 

 buds, and in this way arise the first rudi- 

 ments of the subsequent lobes (Fig. 273, ^). 

 These are, at first, nothing but minute pyri- 

 form- or flask-shaped processes of the com- 

 mon rudiment of the gland, which do not 

 separate from each other until towards the 

 end of fostal life, at which time they open 

 externally ; whilst, at the same time, rounded 

 or elongated solid buds begin to appear at 

 their ends, which at this time are also solid. 

 At the period of birth, the gland measures 

 from li-4 lines, and already distinctly ex- 

 hibits a certain number (12-15) divisions, of 



which the internal still approximate the rudimentary papilke, in fact 

 have either simple flask-like ends, or terminate in two or three sinuosi- 

 ties; whilst the others are in connection with a greater number. The ex- 

 cretory duct of each of these rudimentary lobules, which is either simple 

 or possesses two or three branches, is composed of a fibrous membrane 

 of immature, nucleated connective tissue, and an epithelium of small 

 cylindrical cells, and is manifestly hollow; whilst the dilated ends, 

 which cannot in this case, any more than in other glands in the process 

 of development, at this time be termed terminal vesicles, are still solid ; 

 being wholly composed, besides the fibrous tunic continued upon them 

 from the ducts, of minute nucleated cells. From this very simple form, 

 the latter one is thus developed : by the long-continued gemmation of 

 the primary and subsequently formed, clavate ends, and their simulta- 

 neous excavation, a much-branched duct, beset in its offsets with whole 

 groups of hollow gland-vesicles, is at last formed. These processes, 



Fig. 273. — Development of the lacteal gland. 1, rudiment of the gland in a male embryo, 

 at five months ; a, horny layer ; 6, mucous layer of the epidermis ; c, process of the latter or 

 rudiment of the gland ; d, fibrous membrane around the same. 2, lacteal gland of a female 

 fcetus, at seven months, seen from above: a, central substance of the gland, witli larger (b) 

 and smaller (c) solid outgrowths, the rudiments of the large gland-lobes. 



&^c 



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