Biology Reference
In-Depth Information
Figure 2.
Histological changes in pituitary TSH cells and thyroid follicles during metamorphosis
of the Japanese fl ounder.
1a-f.
Larval development. (a)
Premetamorphic larva 4 days after hatching. Absorption of yolk
almost completed. (b) Symmetrical pelagic larva at premetamorphosis 20 days after hatching.
Note several elongated dorsal fi n rays (arrowhead).
(c)
Larva at prometamorphic stage 30
days after hatching. The right eye has started to migrate. (d)
Larva at metamorphic climax
50 days after hatching. (e) Fish almost completed metamorphosis (post climax) 60 days after
hatching. The anterior margin of the dorsal fi n is blackened by melanin granules (arrowhead).
(f) Jvenile 80 days after hatching. a ×16; b ×9.0; c ×5.5; d ×3.9; e× 4.1; f ×2.2.
2a
f
. Midsagittal sections of pituitary gland stained with anti-hTSHβ. Anterior direction is left.
(a)
Some immunoreactive TSH (Ir TSH) cells are clearly seen. Cartilage is stained with methyl
green. (b) Ir TSH cells are located in the dorsal part of the proximal pars distalis (PPD). (c)
Ir TSH cells are observed not only in the dorsal part but also in the ventral part of PPD. (d)
Immunoreactivity is less than that in 30 day-old fi sh (2c). The Ir TSH cells are not observed in
the ventral part of PPD. (e) Intensity of immunostaining is weak. the Ir TSH cell area is small
and limited to the dorsal part of PPD. (f) IrTSH cells are stained strongly with the antiserum
although the cell area is not so extended as in the fi sh at prometamorphosis (2c). C, cartilage;
H, hypothalamus; N, neurohypophysis. A-f ×660.
3a-f.
Sagittal section of the thyroid gland stained with HE. (a) Two thyroid follicles are seen
(arrowheads). (b) The number of the follicles (arrowheads) is increasing. (c) The epithelial
cells of the follicles are higher than in 20-day-old fi sh (3b). (d) Epithelial cells are tall. Note
that each epithelial cell has enlarged nucleus and a vacuole-like structure. (e) Epithelial cells
are fl attened and have small nuclei, suggesting very low activity at this stage. The follicles
are fi lled homogenously with eosinophillic colloid.
f,
Follicular cells are higher in 60-day old
fi sh (3e), suggesting reactivation of the thyroid gland. A-f ×271. [From Miwa and Inui, 1987
with permission].
