The anatomy and histology of the adult female mosquito / by S. R. Christophers.

  • Christophers, S. R.
Date:
1901
Catalogue details

Licence: In copyright

Credit: The anatomy and histology of the adult female mosquito / by S. R. Christophers. Source: Wellcome Collection.

Provider: This material has been provided by London School of Hygiene & Tropical Medicine Library & Archives Service. The original may be consulted at London School of Hygiene & Tropical Medicine Library & Archives Service.

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    the extreme periphery, and the nucleus, which is much degenerated, is pushed to the outer portion of the cell, and usually lies in the angixliir interval left at the base of two or more contiguous cells. In the granular type of gland this disappearance of the protoplasm and nucleus from view is more ijronounced than in the clear type of gland. The Clear or Colloid-lilce Type.—Of the last-mentioned type there are two acini upon either side; of the present type there is but a single acinus upon either side, which usuall}'^ lies between the two acini of granular type. (Plate 5, fig. 7.) In the fresh gland the cell outlines are not so distinct as in the granular type, and the secretion when extended by pressure is much less refractive. In alcohol-hardened specimens, the acinar cells contain a large mass of clear homogeneous secretion v'hich, as in the last- mentioned type, fills almost the entire cell, and pushes the protoplasm and nucleus to the periphery. In the clear type, however, the protoplasm is always in greater amount than is the case with the granular type, and the nucleus never becomes so greatly degenerated. The clear homogeneous sedition stains readily with haematein, and may even stain quite deeply. With Heidenhein’s hrematoxylin it frequently becomes almost Ijlack. It resembles very much in appearance colloid substance as it is seen in the mammalian thyroid. In Anopheles this substance also distends the central duct space Avithin the acinus. In this situation an appearance is sometimes pro- duced which resembles faintly-stained sporozoites, but which is a normal condition. The Maturation of the Glands.—In freshly-hatched mosquitoes both types of acinus consist of large glandular cells arranged round the lumen. These contain a large centrally situated nucleus, and haA'e- protoplasm containing a large number of coarse granules staining with htemateih. In the portion of the cell nearest the lumen a vacuole of varying size is situated. This is the commencement of the large mass of secretion Avhich, in the mature gland, occupies the entire cell. In the granular type of acinus the vacuole contains granules; in the clear type it resembles the colloid-like secretion. (Plate 5, fig. 8.) Further Variations in the Cells of the Salivary Acini.—In the granular type of gland the greater portion of the acinus is composed of cells of the character described above. A jDortion, however, usually exists which difiers considerably in structure. This portion adjoins the duct, and may in Anopheles reach as much as one-quarter of the entire gland in length. In this portion of the gland the cells are much smaller than those containing the granular secretion, so that the diameter of the acinus is much less here, and a sudden increase takes place when the portion containing the gramdar secretion is reached. The cells lying towards the duct differ from those lying toAvards the acinar end of this