Ultrastructural Comparison of Processing of Protein and Pigment in the Ink Gland of Four Species of Sea Hares

Table 1

Characteristics of the ink gland of four species of sea hare.

	Sea hare species
	A. californica	A. juliana	A. parvula	D. dolabrifera
RER cells
Abundant rer	+	+	+	−
Condensed rer	−	+	−	−
Microtubule in vacuoles	−	−	+	−
Number of caveolae^(1)	0.4 ± 0.2^(2)	0.2 ± 0.3^(2)	3.3 ± 0.7^(2)	2.3 ± 0.4^(2)
Caveolar shape	Balloon	Balloon	Balloon	Long and Branched
Nucleolus	+	+	+	−
Granulate cells
Nucleolus	−	+	+	−
Sieve areas	+	+	+	+
Granules	Diet dependent	+	+	−
RER and granulate cell
Abundance	Many	Many	Many	Few
Spacing in gland	Close	Close	Close	Dispersed
Vesicle type
Purple	Pigment	Pigment	Pigment	−
Amber^(4)	Protein	−	−	−
Clear^(5)	Electron-lucent with sheets	−	−	−
White^(4)	−	Protein	Protein	−
Transparent^(5)	−	−	−	Electron-lucent with tubes
Protein in vesicles
Lattice dimensions	37 ± 6 nm^(2)	46 ± 10 nm^(2)	36 ± 11 nm^(2)	15 ± 2 nm^(2,3)

(1) = number/length of cell membranes in µm; (2) = mean ± SD; (3) = in cells beneath epidermis; (4) = amber and white vesicles now termed protein vesicles; (5) = clear vesicles now termed transparent vesicles.