Neurons in larvae of Acila insignis immunostained positively for serotonin. Green = immunostaining for 5-HT; red = immunostaining for alpha-acetylated tubulin; blue = staining with DAPI. (A-D) Projections of whole larvae; (A1-D1) separate Z projections; (A2-A4, B2, B3, C2, C3, D2, D3) higher magnification of neuron bodies; and (A5, B4, C4, D4) graphical interpretation of the immunostainings. (A-A5) A 30 hpf pericalymma larva. (A, A1) The first two 5-HT-LIP neurons in the apical organ (AO) appear at the anterior pole of the larva (1 and 2). (A2-A4) The first two 5-HT-LIP cells (indicated by numbers 1, 2 in A1). (A5) A 30 hpf pericallymmal larva with two 5-HT-labelled cells in the AO and an apical tuft. (B-B4) A 36 hpf pericalymma larva; (B, B1) three 5-HT-LIP neurons (1, 2, and 3) with common neuropils (n) in the AO in the anterior part of the larva; (B2) a neuropil connecting neurons 1 and 3; (B3) a neuropil at the base of neuron 2; (B4) a 36 hpf pericalymma larva with AO consisting of three cells immunostaining for 5-HT and an apical tuft. (C-C4) A late pericalymma larva; (C, C1) AO contains three flask-shaped 5-HT-LIP neurons (1, 2 and 3) connected by neuropils; (C2, C3) no signal is visible in other parts of the larva; (C4) a late pericalymma larva devoid of an apical tuft and with an AO consisting of three flask-shaped 5-HT-LIP cells. (D-D4) A metamorphic pericalymma larva (D, D1) with disrupted test cells (TS) and an AO organized in the same manner as at previous stages, i.e., with three flask-shaped neurons and neuropils (D2,D3); (D4) a metamorphic larva with an AO consisting of three flask-shaped 5-HT-LIP cells. The letter designations are as follows: a, anus; AO, apical organ; at, apical tuft; cb, band of cilia; es, esophagus; in, intestine; m, mouth; n, neuropil; st, stomach; TS, test cells. Scale bars = 100 μm.

Contexts in source publication

Context 1

... the early stages of development (15 and 21 hpf), we observed no 5-HT-like immunopositive (LIP) signals (Fig. 1A2, B2). The first serotonergic neurons appear at the early pericalymma stage (30 hpf, Fig. 3A) in the anterior part of the larva (Fig. 3A1). The first two of these neurons (Fig. 3A2-A4) are part of the apical organ (AO) (Fig. 3A5). Shortly after, at 36 hpf, the third 5-HT-LIP cell appeared adjacent to the previous two (Fig. 3B), which then developed neurites connecting to this third cell (Fig. 3B1), thereby forming a network of ...

Context 2

... the early stages of development (15 and 21 hpf), we observed no 5-HT-like immunopositive (LIP) signals (Fig. 1A2, B2). The first serotonergic neurons appear at the early pericalymma stage (30 hpf, Fig. 3A) in the anterior part of the larva (Fig. 3A1). The first two of these neurons (Fig. 3A2-A4) are part of the apical organ (AO) (Fig. 3A5). Shortly after, at 36 hpf, the third 5-HT-LIP cell appeared adjacent to the previous two (Fig. 3B), which then developed neurites connecting to this third cell (Fig. 3B1), thereby forming a network of 5-HT-LIP cells (neuropil) (Fig. 3B2-B4). Thereafter, at the late pericalymma stage (72 hpf), the number and location of these 5-HT-LIP ...

Context 3

... (LIP) signals (Fig. 1A2, B2). The first serotonergic neurons appear at the early pericalymma stage (30 hpf, Fig. 3A) in the anterior part of the larva (Fig. 3A1). The first two of these neurons (Fig. 3A2-A4) are part of the apical organ (AO) (Fig. 3A5). Shortly after, at 36 hpf, the third 5-HT-LIP cell appeared adjacent to the previous two (Fig. 3B), which then developed neurites connecting to this third cell (Fig. 3B1), thereby forming a network of 5-HT-LIP cells (neuropil) (Fig. 3B2-B4). Thereafter, at the late pericalymma stage (72 hpf), the number and location of these 5-HT-LIP cells did not changed (Fig. 3C, С1), but all three had a clear flask-like shape at this stage ( Fig. ...

Context 4

... the sensory AO consisted of three 5-HT-LIP cells: two bilaterally symmetrical flask-shaped cells connected to an additional flask-shaped cell, their neurites formed the compact neuropile (Fig. 3C4, ...

Context 5

... cell (Fig. 4B1), as well as two bright FMRFamide-LIP cells in the posterior part (Fig. 4B, B2, B3). By 96 hpf, one flask-shaped FMRFamide-LIP cell in the AO (Fig. 4C, C1) and two rounded FMRFamide-LIP cells close to the lower intestine (Fig. 4C, C2) were present, along with two additional FMRFamide-LIP cells below and dorsally to the AO (Fig. 4C, C3, C4). No neurites with connections to all three of these FMRFamide-LIP regions were detected (Fig. 4C, C4). (Fig. 5A, A1). The subsequent neurodevelopment is accompanied by the appearance of additional FMRFamide-LIP structures only. By 96 hpf, in addition to the AO, posterior dorsal neurons appeared (Fig. 5B, B1). No neurites ...