{'fraction_non_alphanumeric': 0.02666666666666667, 'fraction_numerical': 0.011428571428571429, 'mean_word_length': 5.2047244094488185, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Pineal canaliculi: demonstration, twenty-four-hour rhythmicity and experimental modification.

Parenchymal perfusions of rat pineal glands with India ink solutions reveal an extravascular and intercellular system of continuous microscopic channels containing ink perfusate. This system has two, apparently interconnecting, components: pericapillary sleeves or networks, and intralobular canaliculi 0.2–0.4 μ in diameter and enmeshing the pinealocytes individually. 
 
 
 
Perfusion of the canaliculi was reduced or inhibited by either partial dehydration or exposure to hypertonic solutions, and was blocked when the perfusate contained either CaCl2 or trypsin. Hyaluronidase was without effect. The extent to which the canaliculi could be perfused followed a 24-hour-rhythm with a peak (mean maximal canalicular perfusion distance = 95 μ) near the end of the daily environmental light phase, and a trough (mean maximal canalicular perfusion distance = 13 μ) during the dark phase. This rhythm resembles that in rat pineal content of 5-hydroxytryptamine. Dark-phase perfusion distances equivalent to those of the light-phase were obtained when 5-hydroxytryptamine (5 × 10−3 M) was present in the perfusate. In similar circumstances norepinephrine, heparin and melatonin were without effect. 
 
 
 
It is suggested that this system of canaliculi may be significant for transport activities between pinealocytes and capillaries and that its circadian and local patency may be regulated in part by release of 5-hydroxytryptamine by the pinealocytes, and in part by calcium ions.